85 lines
2.6 KiB
ArmAsm
85 lines
2.6 KiB
ArmAsm
/*
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* Copyright (c) 1992 Helsinki University of Technology
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* HELSINKI UNIVERSITY OF TECHNOLOGY ALLOWS FREE USE OF THIS SOFTWARE IN
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* ITS "AS IS" CONDITION. HELSINKI UNIVERSITY OF TECHNOLOGY DISCLAIMS ANY
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* LIABILITY OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE
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* USE OF THIS SOFTWARE.
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*/
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/*
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* HISTORY
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* 29-Apr-92 Tero Kivinen (kivinen) at Helsinki University of Technology
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* Created.
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*
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* $Id: ldexp.s,v 1.1.1.1 1993/09/17 18:43:47 phil Exp $
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*/
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/*
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* double ldexp (value, exp)
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* double value;
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* int exp;
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*
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* Ldexp returns value*2**exp, if that result is in range.
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* If underflow occurs, it returns zero. If overflow occurs,
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* it returns a value of appropriate sign and largest
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* possible magnitude. In case of either overflow or underflow,
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* errno is set to ERANGE. Note that errno is not modified if
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* no error occurs.
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*/
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#include <machine/asm.h>
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#define ERANGE 34
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.globl EX(errno)
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ENTRY(ldexp)
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enter [],8
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movd 12(fp),r1 /* get value, high 32 bit */
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lshd -20,r1 /* extract exponent */
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andd 0x7ff,r1 /* 11 lower bits */
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subd 1023,r1 /* unbias exponent */
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movd 16(fp),r0 /* get exp */
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addd r1,r0 /* add exponents */
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cmpd r0,1023 /* most positive exponent */
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bgt ldexp_overflow /* too large */
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cmpd r0,-1022 /* most negative exponent */
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blt ldexp_underflow /* too small */
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addd 1023,r0 /* bias exponent */
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lshd 20,r0 /* convert exponent back to its place */
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movd 12(fp),r1 /* get value high 32 bit */
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bicd 0x7ff00000,r1 /* clear exponent */
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ord r0,r1 /* insert exponent */
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movd r1,-4(fp) /* put high 32 bit to local variable */
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movd 8(fp),-8(fp) /* value low 32 bit to local variable */
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movl -8(fp),f0 /* return value * 2**exp */
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exit []
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ret 0 /* neither */
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ldexp_underflow:
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movdl 0d0e0,f0 /* if underflow return 0, set errno */
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movd ERANGE,@EX(errno)
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exit []
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ret 0
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ldexp_overflow:
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movl @huge,f0 /* if overflow return HUGE */
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movdl 0d0e0,f2
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cmpl f2,8(fp) /* check original sign */
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bgt ldexp_positive
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negl f0,f0 /* if negative, return -HUGE */
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ldexp_positive:
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movd ERANGE,@EX(errno) /* set errno */
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exit []
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ret 0
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huge: .long 0xffffffff /* the largest number that can */
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.long 0x7fefffff /* be represented in a long floating */
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/* number. This is given in hex in order */
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/* to avoid floating conversions */
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